Carmoxirole (EMD 45 609) is a new synthetic dopamine receptor agonist that is undergoing Phase II clinical trials in the USA. This study will address the safety and efficacy of three doses of carmoxirole (0.5, 1.0 and 2.0) administered once daily in patients with essential hypertension. Because of the occurrence of significant orthostatic hypotension following the first dose, patients will be carefully monitored in the GCRC for the occurrence of this effect.